philips size 1 and 2 (the + shaped ones)
big flathead (mine's 5.5mm but there's some margin in possibilities there)
small flathead (3mm, same margin as before)
and some universal pliers
those should be all you need to get everythign sorted, there's probably an endless list of "creature comfort" things you can add, but this is somewhat the basics for just about anything you'll encounter in computer building.
oh, and please, get magnetic screwdrivers if you can, that's the one creature comfort that i'd value above the others.